This is the mail archive of the
binutils@sourceware.org
mailing list for the binutils project.
[PATCH] PR ld/19636: pie changes program behavior and generate unnecessary dynamic symbols
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: binutils at sourceware dot org
- Date: Mon, 15 Feb 2016 07:00:32 -0800
- Subject: [PATCH] PR ld/19636: pie changes program behavior and generate unnecessary dynamic symbols
- Authentication-results: sourceware.org; auth=none
Non-dynamic symbols are always bound locally in PIE and we always create
the dynsym section, even if it is empty, with dynamic sections.
I fixed x86. Other backends need similar fix. Any comments?
Thanks.
H.J.
---
bfd/
PR ld/19636
* elf32-i386.c (elf_i386_allocate_dynrelocs): Discard relocations
on locally bound weak undefined symbols.
(elf_i386_relocate_section): Don't generate dynamic relocations
against locally bound weak undefined symbols.
* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): Discard
relocations on locally bound weak undefined symbols.
(elf_x86_64_relocate_section): Don't generate dynamic relocations
against locally bound weak undefined symbols.
* elflink.c (bfd_elf_record_link_assignment): Make the linker
assigned symbol dynamic for shared library or relocatable
executable.
(_bfd_elf_link_renumber_dynsyms): Check for shared library,
instead of PIC. Always create the dynsym section, even if it is
empty, with dynamic sections.
(bfd_elf_final_link): Check for shared library, instead of PIC,
when writing out the section symbols.
ld/
PR ld/19636
* testsuite/ld-elf/pr19636.s: New file.
* testsuite/ld-elf/pr19636a.d: Likewise.
* testsuite/ld-elf/pr19636b.d: Likewise.
* testsuite/ld-x86-64/pr13082-3b.d: Updated.
* testsuite/ld-x86-64/pr13082-4b.d: Likewise.
---
bfd/elf-bfd.h | 15 ++++++++++-----
bfd/elf32-i386.c | 17 ++++++++++++-----
bfd/elf64-x86-64.c | 16 +++++++++++-----
bfd/elflink.c | 14 +++++++-------
ld/testsuite/ld-elf/pr19636.s | 5 +++++
ld/testsuite/ld-elf/pr19636a.d | 10 ++++++++++
ld/testsuite/ld-elf/pr19636b.d | 12 ++++++++++++
ld/testsuite/ld-x86-64/pr13082-3b.d | 4 +---
ld/testsuite/ld-x86-64/pr13082-4b.d | 4 +---
9 files changed, 69 insertions(+), 28 deletions(-)
create mode 100644 ld/testsuite/ld-elf/pr19636.s
create mode 100644 ld/testsuite/ld-elf/pr19636a.d
create mode 100644 ld/testsuite/ld-elf/pr19636b.d
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index ea4d59a..c9884d5 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -2639,11 +2639,16 @@ extern asection _bfd_elf_large_com_section;
continue; \
}
-/* Will a symbol be bound to the definition within the shared
- library, if any. A unique symbol can never be bound locally. */
-#define SYMBOLIC_BIND(INFO, H) \
- (!(H)->unique_global \
- && ((INFO)->symbolic || ((INFO)->dynamic && !(H)->dynamic)))
+/* Will a symbol be bound to the definition within the PIC object, if
+ any. A unique symbol can never be bound locally. Non-dynamic symbol
+ is always bound locally in PIE. */
+#define SYMBOLIC_BIND(INFO, H) \
+ (!(H)->unique_global \
+ && ((INFO)->symbolic \
+ || ((INFO)->dynamic && !(H)->dynamic) \
+ || (!(INFO)->export_dynamic \
+ && !(INFO)->dynamic \
+ && bfd_link_pie (INFO))))
#ifdef __cplusplus
}
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index a8951d8..a12b161 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -2611,11 +2611,12 @@ elf_i386_allocate_dynrelocs (struct elf_link_hash_entry *h, void *inf)
}
/* Also discard relocs on undefined weak syms with non-default
- visibility. */
+ visibility or bound locally. */
if (eh->dyn_relocs != NULL
&& h->root.type == bfd_link_hash_undefweak)
{
- if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
+ if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+ || SYMBOLIC_BIND (info, h))
eh->dyn_relocs = NULL;
/* Make sure undefined weak symbols are output as a dynamic
@@ -4244,11 +4245,15 @@ r_386_got32:
|| is_vxworks_tls)
break;
- /* Copy dynamic function pointer relocations. */
+ /* Copy dynamic function pointer relocations. Don't generate
+ dynamic relocations against locally bound weak undefined
+ symbols. */
if ((bfd_link_pic (info)
&& (h == NULL
- || ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
- || h->root.type != bfd_link_hash_undefweak)
+ || (!(h->root.type == bfd_link_hash_undefweak
+ && SYMBOLIC_BIND (info, h))
+ && (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+ || h->root.type != bfd_link_hash_undefweak)))
&& ((r_type != R_386_PC32 && r_type != R_386_SIZE32)
|| !SYMBOL_CALLS_LOCAL (info, h)))
|| (ELIMINATE_COPY_RELOCS
@@ -4256,6 +4261,8 @@ r_386_got32:
&& h != NULL
&& h->dynindx != -1
&& (!h->non_got_ref || eh->func_pointer_refcount > 0)
+ && !(h->root.type == bfd_link_hash_undefweak
+ && SYMBOLIC_BIND (info, h))
&& ((h->def_dynamic
&& !h->def_regular)
|| h->root.type == bfd_link_hash_undefweak
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 463ce3a..fddd394 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -2832,12 +2832,13 @@ elf_x86_64_allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf)
}
/* Also discard relocs on undefined weak syms with non-default
- visibility. */
+ visibility or bound locally. */
if (eh->dyn_relocs != NULL)
{
if (h->root.type == bfd_link_hash_undefweak)
{
- if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT)
+ if (ELF_ST_VISIBILITY (h->other) != STV_DEFAULT
+ || SYMBOLIC_BIND (info, h))
eh->dyn_relocs = NULL;
/* Make sure undefined weak symbols are output as a dynamic
@@ -4585,7 +4586,8 @@ direct:
/* Don't copy a pc-relative relocation into the output file
if the symbol needs copy reloc or the symbol is undefined
when building executable. Copy dynamic function pointer
- relocations. */
+ relocations. Don't generate dynamic relocations against
+ locally bound weak undefined symbols. */
if ((bfd_link_pic (info)
&& !(bfd_link_executable (info)
&& h != NULL
@@ -4594,8 +4596,10 @@ direct:
|| h->root.type == bfd_link_hash_undefined)
&& IS_X86_64_PCREL_TYPE (r_type))
&& (h == NULL
- || ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
- || h->root.type != bfd_link_hash_undefweak)
+ || (!(h->root.type == bfd_link_hash_undefweak
+ && SYMBOLIC_BIND (info, h))
+ && (ELF_ST_VISIBILITY (h->other) == STV_DEFAULT
+ || h->root.type != bfd_link_hash_undefweak)))
&& ((! IS_X86_64_PCREL_TYPE (r_type)
&& r_type != R_X86_64_SIZE32
&& r_type != R_X86_64_SIZE64)
@@ -4605,6 +4609,8 @@ direct:
&& h != NULL
&& h->dynindx != -1
&& (!h->non_got_ref || eh->func_pointer_refcount > 0)
+ && !(h->root.type == bfd_link_hash_undefweak
+ && SYMBOLIC_BIND (info, h))
&& ((h->def_dynamic
&& !h->def_regular)
|| h->root.type == bfd_link_hash_undefweak
diff --git a/bfd/elflink.c b/bfd/elflink.c
index ac03ce5..c3fa20d 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -632,8 +632,8 @@ bfd_elf_record_link_assignment (bfd *output_bfd,
if ((h->def_dynamic
|| h->ref_dynamic
- || bfd_link_pic (info)
- || (bfd_link_pde (info)
+ || bfd_link_dll (info)
+ || (bfd_link_executable (info)
&& elf_hash_table (info)->is_relocatable_executable))
&& h->dynindx == -1)
{
@@ -844,7 +844,7 @@ _bfd_elf_link_renumber_dynsyms (bfd *output_bfd,
{
unsigned long dynsymcount = 0;
- if (bfd_link_pic (info)
+ if (bfd_link_dll (info)
|| elf_hash_table (info)->is_relocatable_executable)
{
const struct elf_backend_data *bed = get_elf_backend_data (output_bfd);
@@ -875,9 +875,9 @@ _bfd_elf_link_renumber_dynsyms (bfd *output_bfd,
&dynsymcount);
/* There is an unused NULL entry at the head of the table which
- we must account for in our count. Unless there weren't any
- symbols, which means we'll have no table at all. */
- if (dynsymcount != 0)
+ we must account for in our count. We always create the dynsym
+ section, even if it is empty, with dynamic sections. */
+ if (elf_hash_table (info)->dynamic_sections_created)
++dynsymcount;
elf_hash_table (info)->dynsymcount = dynsymcount;
@@ -11484,7 +11484,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
long last_local = 0;
/* Write out the section symbols for the output sections. */
- if (bfd_link_pic (info)
+ if (bfd_link_dll (info)
|| elf_hash_table (info)->is_relocatable_executable)
{
asection *s;
diff --git a/ld/testsuite/ld-elf/pr19636.s b/ld/testsuite/ld-elf/pr19636.s
new file mode 100644
index 0000000..9bd7e4a
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr19636.s
@@ -0,0 +1,5 @@
+ .text
+ .weak func
+ .globl _start
+_start:
+ .dc.a func
diff --git a/ld/testsuite/ld-elf/pr19636a.d b/ld/testsuite/ld-elf/pr19636a.d
new file mode 100644
index 0000000..f645d09
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr19636a.d
@@ -0,0 +1,10 @@
+#source: pr19636.s
+#ld: -pie
+#readelf : -r --dyn-syms --wide
+#target: x86_64-*-linux* i?86-*-linux-gnu
+
+There are no relocations in this file.
+
+Symbol table '\.dynsym' contains 1 entries:
+ +Num: +Value +Size Type +Bind +Vis +Ndx Name
+ +0: 0+ +0 +NOTYPE +LOCAL +DEFAULT +UND +
diff --git a/ld/testsuite/ld-elf/pr19636b.d b/ld/testsuite/ld-elf/pr19636b.d
new file mode 100644
index 0000000..3b4d22f
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr19636b.d
@@ -0,0 +1,12 @@
+#source: pr19636.s
+#ld: -pie -E
+#readelf : -r --dyn-syms --wide
+#target: *-*-linux* *-*-gnu* *-*-solaris*
+
+Relocation section '\.rela?\..*' at offset 0x[0-9a-f]+ contains [0-9]+ entries:
+#...
+Symbol table '\.dynsym' contains [0-9]+ entries:
+ +Num: +Value +Size Type +Bind +Vis +Ndx Name
+#...
+ +[0-9]+: +[a-f0-9]+ +0 +NOTYPE +WEAK +DEFAULT +UND +func
+#...
diff --git a/ld/testsuite/ld-x86-64/pr13082-3b.d b/ld/testsuite/ld-x86-64/pr13082-3b.d
index 12efaf0..766dd74 100644
--- a/ld/testsuite/ld-x86-64/pr13082-3b.d
+++ b/ld/testsuite/ld-x86-64/pr13082-3b.d
@@ -4,6 +4,4 @@
#ld: -pie -melf32_x86_64
#readelf: -r --wide
-Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 1 entries:
- Offset Info Type Sym. Value Symbol's Name \+ Addend
-[0-9a-f]+ +[0-9a-f]+ +R_X86_64_32 +[0-9a-f]+ +func \+ 0
+There are no relocations in this file.
diff --git a/ld/testsuite/ld-x86-64/pr13082-4b.d b/ld/testsuite/ld-x86-64/pr13082-4b.d
index cb4d90a..6d4a35b 100644
--- a/ld/testsuite/ld-x86-64/pr13082-4b.d
+++ b/ld/testsuite/ld-x86-64/pr13082-4b.d
@@ -4,6 +4,4 @@
#ld: -pie -melf32_x86_64
#readelf: -r --wide
-Relocation section '.rela.dyn' at offset 0x[0-9a-f]+ contains 1 entries:
- Offset Info Type Sym. Value Symbol's Name \+ Addend
-[0-9a-f]+ +[0-9a-f]+ +R_X86_64_64 +[0-9a-f]+ +func \+ 1
+There are no relocations in this file.
--
2.5.0